DOVER — A New Jersey National Guard armory was shut down in May as officials investigated a suspicious package that turned out to be harmless — containing only a box of recruitment brochures, police said.

A bomb robot, like the one seen in this Jersey Journal file photo, helped authorities determine a suspicious package found at the National Guard armory in Dover was harmless.Reena Rose

The incident took place May 7, but Rockaway Township police first issued a statement to press describing the incident last week.

According to the statement, around 7:30 a.m., an Army representative noticed the brown cardboard box by a doorway. He described it as being about 10 by 12 inches, with a National Guard label on it — the kind usually used by recruiters for mailing — police said. The box was closed, but not sealed, police said.

Army representatives made several calls to determine why the box would be there, but couldn't find any answers, so they placed several sand bags near the box and called police, according to the statement.

The National Guard evacuated the building and blocked access to it, police said.

Morris County's bomb squad, K9 units and prosecutor's office all came to the scene, police said. The bomb squad approached the box with a bomb robot and took an X-ray photo, which found no hazardous materials, police said.

The building was reopened for business after officials determined the box only contained recruitment brochures.